1. Field of the Invention
The present invention relates to an endoscope configured by fixing an end portion having an emission end face of a light guide fiber within a concave portion corresponding to an illuminating window portion formed of a transparent resin member.
2. Description of the Related Art
Endoscopes are widely used in medical and industrial fields. Examples of diagnostic or observation targets of an endoscope include interiors of a living body and a plant. For this reason, an endoscope apparatus requires a light source for illuminating a diagnostic or observation target.
A typical endoscope apparatus is provided with an endoscope and a light source apparatus as an endoscope external apparatus. The light source apparatus incorporates a light emission source that emits illuminating light such as a lamp or a light-emitting device.
The illuminating light emitted from the light emission source is transmitted by a light guide fiber provided in the endoscope and passes through an illuminating window provided at a distal end of an insertion portion to illuminate an observation target.
For example, Japanese Patent Application Laid-Open Publication No. 2009-207529 discloses an endoscope that can obtain a sufficient light quantity and a satisfactory light distribution, prevent losses in the light quantity, and has a small-diameter distal end. The distal end portion of the endoscope is formed of a transparent member through which illuminating light passes. The distal end portion is provided with an insertion part through which an observation optical system is inserted and an insertion portion into which a light guide fiber is inserted. A lens system having a predetermined function is formed at the distal end portion of the insertion portion.
According to Japanese Patent Application Laid-Open Publication No. 2009-207529, the insertion portion is disposed in a substantially annular shape so as to surround the insertion part. For this reason, the light guide fiber and the lens system are also disposed in a substantially annular shape so as to surround the observation optical system. The insertion portion is provided, on the proximal end side, with a prevention portion configured to prevent the distal end of the light guide fiber from being inserted as far as the distal end side of the lens system and dispose the fiber on the proximal end side of the lens system.
According to the configuration, when the light guide fiber is inserted into the insertion portion, the distal end of the fiber collides with the prevention portion, is thereby disposed at a predetermined position on the proximal end side, and stands face to face with the lens system.
As a result, when the light source apparatus emits irradiation light, the light guide fiber radiates the irradiation light from the distal end. The irradiation light radiated from the distal end is spread by the lens system, passes through the distal end portion, is radiated forward from a front end face side, passes through the distal end portion, enters a slope portion, is radiated from the slope portion side and illuminates interiors of a body cavity, thus enabling satisfactory observation.